Brett Coomer: Chronicle
AND THE CROWD GOES MILD: The noise at Reliant Stadium dipped to church-mouse levels Sunday when Texans wide receiver Andre Johnson (80) went down with a hamstring injury. Johnson left the game, and the severity of the injury still is unknown.

Photo: Brett Coomer

Brett Coomer: Chronicle
AND THE CROWD GOES MILD: The noise at...

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Houston Texans wide receiver Andre Johnson leaves the game after going down with an apparent hamstring injury.

Photo: Nick De La Torre, Houston Chronicle

Houston Texans wide receiver Andre Johnson leaves the game after...

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Houston Texans wide receiver Andre Johnson (80) is tackled by Pittsburgh Steelers cornerback Ike Taylor (24) during the second quarter of an NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston.

Photo: Brett Coomer, Houston Chronicle

Houston Texans wide receiver Andre Johnson (80) is tackled by...

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Houston Texans wide receiver Andre Johnson (80) can't hold onto a pass as Pittsburgh Steelers cornerback Ike Taylor (24) defends during the first quarter of an NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston.

Photo: Brett Coomer, Houston Chronicle

Houston Texans wide receiver Andre Johnson (80) can't hold onto a...

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Houston Texans wide receiver Andre Johnson reacts after being shaken up on a play against the Pittsburgh Steelers during the second quarter of a NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston. Johnson left the game after the play.

Photo: Nick De La Torre, Houston Chronicle

Houston Texans wide receiver Andre Johnson reacts after being...

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Houston Texans wide receiver Andre Johnson (80) prepares to take the field against the Pittsburgh Steelers for an NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston.

Photo: Brett Coomer, Houston Chronicle

Houston Texans wide receiver Andre Johnson (80) prepares to take...

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Houston Texans wide receiver Andre Johnson receives attention after being shaken up on a play against the Pittsburgh Steelers during the second quarter of a NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston.

Houston Texans wide receiver Andre Johnson (80) slips to the turf as Pittsburgh Steelers cornerback William Gay (22) defends during the second quarter of a NFL football game at Reliant Stadium on Sunday, Oct. 2, 2011, in Houston. Johnson left the game after the play.

In his magnificent nine-year career, Texans receiver Andre Johnson has missed more than three games in a season one time.

In 2007, Gary Kubiak's second season as coach, Johnson suffered ligament damage in his knee and missed seven games. The Texans went 2-5 without him.

On Monday, Kubiak said the Texans don't know the extent of Johnson's hamstring injury, despite multiple MRIs. Now Johnson is headed for a second and perhaps third opinion before they'll have a proper prognosis for his return.

"It's hard for me to give you an answer right now," Kubiak said Monday. "He's going to miss some time. I don't know if that's three or four days. I don't know if that's a few weeks.

"We're dealing with a hamstring — we know that. We're still in an evaluation process. We're going to get a couple different opinions over the course of the next two days. Once we get a better evaluation and see how he progresses over the next two days, I can probably answer your question better."

Johnson suffered the injury without being touched in Sunday's 17-10 victory over Pittsburgh that elevated the Texans' record to 3-1 and kept them in a tie with Tennessee for first place in the AFC South.

Johnson missed three games last season with a high ankle sprain. The Texans went 2-1, including a victory at Oakland, in his absence. The Texans host the Raiders on Sunday.

Although Kubiak didn't rule out Johnson for the Oakland game, it's likely he'll have to sit this one out. Then the question becomes: How many games does he miss?

The Texans should have an idea when Johnson finishes his evaluations.

"A lot of our guys get second opinions on everything we're doing, just trying to decide what's best," Kubiak said. "Obviously, with Andre right now, there's big concern as we move forward.

"At the same time, we've got to do what's best by Andre so that he understands exactly what's going on (and) we understand exactly what's going on."

Jones has seven catches for 91 yards this season, but he and Walter had no receptions Sunday. Quarterback Matt Schaub relied on a running game led by Arian Foster (30 carries, 155 yards) and tight end Owen Daniels, who had five catches for 69 yards and a touchdown.

"I've got a lot of confidence in those guys," Kubiak said. "Jacoby's grown up a lot as a player. He went in (Sunday) and played well. He's much better in the run game than he has been in the past. He's very capable of making big plays.

"If we're missing time with Andre, you don't replace Andre. What you do is you've got to pick it up across the board at other spots. (Daniels) did that for us (on Sunday). If he (Johnson) is going to miss some time, we're just going to have to play better as a group."

The other Johnson

Bryant Johnson, who signed before the last preseason game, has one catch for 16 yards. He would take Jones' spot as the third receiver.

"It's been a mental catch-up thing for Bryant, but he's come a long way," Kubiak said. "He played a little (Sunday). His preparation has been excellent.

"We're going to find out right now how much he can help us, because with Kevin and Jacoby, our third receiver, what he always has to do is be able to go in and play two spots. We'll ask Bryant to do that right away, so we're expecting him to step up and help us."